This reads as: “select every site in sites, remove the ones that aren’t in the Adelaide time zone, select the stations from those, and return their ID”. This generates the same results as the first expressions, but reads pretty much as you’d say it to someone (and there’s no mapcat to forget).

…But it’s when you get to following example, a real part of a system I’ve been working on, that list-comprehension approach comes into its own:

Without going into details, this has three levels of nesting and a filter, generating a series of pairs of station ID’s and tasks to be scheduled for them. For someone familiar with the system, this will be far easier to comprehend than a map/filter.